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Quantitative Analysis of Meiotic Configurations in Tip Sterile Lines of Hexaploid Wheat

Shahriar Zaman*
Department of Genetic Engineering & Biotechnology, University of Rajshahi, Rajshahi 6205 Bangladesh

M. Abdul Mazid
Department of Genetic Engineering & Biotechnology, University of Rajshahi, Rajshahi 6205 Bangladesh

Golam Kabir
Prof. S. Alam Cytogenetics Laboratory, Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh

Abstract/ Executive Summary:

In five tip sterile lines of hexaploid wheat (Kheri, Mexicani, Pavon-76, Seri-82 and Sonora-64) due to interchange of segments three types of meiotic configuration i.e. ring quadrivalent (oIV), chain quadrivalent (cIV) and trivalent plus univalent (III.I) were found at metaphase I. The observed and expected numbers of meiotic configurations in these translocated lines of wheat were found to following the equations based on normal pairing and non random distribution of chiasmata. Different configurations (oIV, cIV, III.I, oII, cII and I) were analyzed following Jackson and Murray’s (1986) formula. The results revealed that χ2 -values for the translocated heterozygotes showed to be fit with the expectation. Data showed good agreement between numbers of expected and observed meiotic configuration and all the lines were in fit to the Ho with p > 0.05.

Keywords: Meiotic configurations, Tip sterility, Hexaploid wheat.

Location: Prof. S. Alam Cytogenetics Laboratory, University of Rajshahi

Start Date: 00-00-2004

End Date: 00-00-2006

Program Area: Variety and Species

Commodity: Wheat

Objectives:

Heterozygous reciprocal translocation can change chiasma frequencies in other chromosomes in the same cell as a result of reduced crossing over in the translocation complex (Sybenga, 1975).These findings obviously claim a quantitative analysis of translocation heterozygote in hexaploid wheat.

Methodology:

The study was conducted in the Prof. S. Alam Cytogenetics Laboratory, University of Rajshahi during the growing seasons of 2004-2006 for studying meiotic configurations in normal line Kanchan and five apical tip sterile translocated varieties/lines of wheat namely Kheri, Mexicani, Pavon-76, Seri-82 and Sonora-64. All these studied plants were grown in earthen pots and the steps adopted are mentioned below: Sampling of plants and collection of inflorescences: At least 10 plants for each of the six variety/lines were selected at random and from these plants inflorescences were collected between 8.30 a.m. to 10.30 a.m. for making observations meiotically. The inflorescences from each variety were fixed for 48 hours in Carnoy’s solution (6 ethanol : 3 chloroform : 1 acetic acid) and then preserved in 70% ethanol and kept in a refrigerator till used. Preparation of slides: For meiotic analysis with special emphasis on meiotic configuration and structural chromosomal changes the temporary slides were prepared from suitable anthers by the standard acetocarmine smear technique. Analysis of meiotic configurations: For making quantitative analysis of meiotic configurations in translocated heterozygotes of wheat along with the normal line, the models and equations proposed by Jackson and Murray (1986) were followed. Here both normal synapses and crossing over, and the reciprocal translocations that affect the normal processes were considered. The chromosomes observed in the karyotypic analysis were either metacentric or submetacentric and thus, there was equal probability that a crossover may occur in either arm. Each bivalent and bivalent equivalent may also have the same opportunity to form chiasma. On the contrary, the equations used for complete pairing and random distribution of 0 to 2 chiasmata/II and 2-4 chiasmata/IV are as follows: oIV = (P4 ) × No. of cells; cIV = 4 (P3 Q1 ) × No. of cells; cIII = 4 (P2 Q2 ) × No. of cells; oII = P2 (n - 2) × No. of cells; cII = 4 (P1 Q1 ) × No. of cells + [2 (PQ) x (n - 2) × No. of cells] ; and I = 2 (Q2 ) × n × No. of cells. These equations were used for random pairing of homologous arms always followed by a crossover and they were also used for determining all expected meiotic configurations in the cell samples.

Source of Information: J. Life Earth Sci., Vol. 6: 13-18, 2011 ISSN 1990-4827

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The results revealed that χ2 -values for the translocated heterozygotes showed to be fit with the expectation. Data showed good agreement between numbers of expected and observed meiotic configuration and all the lines were in fit to the Ho with p > 0.05.

Knowledge Management: Journal